Nonlinear theory of quantum Brownian motion

A nonlinear theory of quantum Brownian motion in classical environment is developed based on a thermodynamically enhanced nonlinear Schrodinger equation. The latter is transformed via the Madelung transformation into a nonlinear quantum Smoluchowski-like equation, which is proven to reproduce key results from quantum and classical physics. The application of the theory to a free quantum Brownian particle results in a nonlinear dependence of the position dispersion on time, being quantum generalization of the Einstein law of Brownian motion. It is shown that the time of decoherence for the transition from quantum to classical diffusion is proportional to the square of the thermal de Broglie wavelength divided by the Einstein diffusion constant

HARP Collaboration results on the proton-nuclei interactions at few GeV energies

Recent results obtained by the HARP collaboration on the measurements of the double-differential production cross-section of positive and negative pions in proton interactions with nuclear targets from Beryllium to Lead are presented. They cover production at small angles (30-210 mrad) and relatively large momenta up to 8 GeV/c as well as large angles (0.35 - 2.15 rad) and small momenta (0.1 - 0.8 GeV/c). These results are relevant for a detailed understanding of neutrino fluxes in accelerator neutrino experiments, better prediction of atmospheric neutrino fluxes, optimization of a future neutrino factory design and for improvement of hadronic generators widely used by the HEP community in the simulation of hadronic interactions.Comment: Talk presented at the XLIII Recontres de Moriond on Electroweak Interactions and Unified Theories, La Thuile, 1-8 March 200